The Taoiseach has said nobody can condone Irish woman Lisa Marie Smith's actions, but she has an innocent two-year-old child in need of consular assistance.
Speaking in the Dáil, Leo Varadkar said that a "security assessment" will be carried out to make sure the Dundalk woman is "not a threat to life and limb here in Ireland".
He confirmed that her case was discussed again at today's Cabinet meeting.
He said: "I am very conscious of the fact that while nobody can condone the choice that she has made and the actions that she took in aligning herself with ISIS, a terrorist regime that is hell-bent on the destruction of the west and Christendom, she does have a two-year-old child that is an Irish citizen and that child is an innocent child.
"And as is the case with all Irish citizens, they will be permitted to re-enter the State should they try to do so".
Mr Varadkar added: "But of course a security assessment will have to be carried out to make sure that Lisa Marie Smith is not a threat to any of us.
"We are working out how best that can be done to make sure that she does not become a threat to life and limb here in Ireland. But that does not apply obviously to a two-year-old child."
The Taoiseach was responding to Labour leader Brendan Howlin who asked about the State's response to Ms Smith's case.
Mr Howlin asked what efforts were being made to return Ms Smith and her daughter to Ireland.
He also asked if it has been determined how Ms Smith will be treated when she arrives home.
Mr Varadkar said suggestions that the Government jet would be used to repatriate Ms Smith and her daughter were "absolutely without foundation".
He said the Government jet is not used to repatriate citizens and it does not fly as far as Syria or Turkey.
He said he is aware of reports that she is in a camp in an area in northern Syria controlled by Kurdish forces.
A woman who was interviewed in the camp containing suspected fighters from the so-called Islamic State, told CNN reporter Jomana Karadsheh Scott that she is Irish and wants to return to Ireland. At no point in the interview did the woman identify herself as Lisa Smith.
Mr Varadkar told the Dáíl that efforts are being made to verify the details and make direct contact with the woman.
He also said that consular assistance is provided to all Irish citizens abroad when requested, "but our capacity to do so in an active war zone is limited.
"Nonetheless I am aware of the vulnerability of the two- year-old child in these circumstances and the safety and welfare of Irish citizens is a priority for the consular service and the Government.
"This applies to the case in question, where two Irish citizens are in high risk locations and wish to leave."
Mr Varadkar said that officials from across Government departments have been meeting to identify options to provide consular assistance to children such as these in Syria.